The invention concerns a brake cylinder device for motor vehicles employing combined pneumatic-hydraulic brake systems.
Such brake cylinder devices are used for power braking control in motor vehicle brake systems with mixed transmitting media, in which a pneumatic pressurizing cylinder is used in combination with a hydraulic transmitting cylinder for pressure transmission, and the transmitting cylinder sends the hydraulic pressure into the wheel cylinder, the forces of which are converted to mechanical movement so as to activate the wheel brakes.
In present designs, the pressurizing cylinder is similar to a diaphragm or a piston cylinder of a pneumatic type vehicle brake system, and the transmitter cylinder is similar to a master cylinder in a hydraulic type vehicle brake system. The housings of the two cylinders are flanged together in the direction of motion of the piston, and a push rod provides a mechanical connection between the diaphragm or piston of the pneumatic pressurizing cylinder and the piston or plunger of the hydraulic transmitter cylinder.
The design of this braking device, however, entails a relatively lengthened construction, so that its installation causes difficulty because of the small amount of available space. The production costs are also high because two separate braking devices must be manufactured, which ultimately perform the braking function of only one braking device within the combined brake system.